Fabrication and microstructual characteristics of germanium spherical semiconductor particles by pulsed orifice ejection method

Germanium spherical particles were prepared by pulsed orifice ejection method. The apparatus was divised for ejecting molten droplet from a small orifice by a reciprocating action of a rod given by piezoelectric actuator. Germanium particles with diameter of several hundreds micrometer could be formed by optimizing process parameters of feeder cross-section area, rod position, supplied pressure and rod displacement. The obtained particles were polycrystal and had microstructure derived either from dendritic growth at a high undercooling or lateral growth at a low undercooling. The latter particles exhibited smaller number of grains than the former ones, and these grain boundaries were twin planes. Finally, solidification mechanisms for the particles were estimated.